Fluid operated devices have been utilized in the textile industry for a number of years as a means for forwarding and processing continuous filamentary materials. Design of such prior fluid operated devices has, in general, been dictated by the intended use of the device. For example, hand held aspirators have been utilized to forward filaments at high speeds from a source adequate to operatively associate the filaments with further processing apparatus operating at high speeds or to waste, such that the source continues to function at normal rates and that sudden shock is not imparted to the filaments adequate to rupture same. Likewise, fluid jet devices have been employed in conjunction with synthetic filamentary materials, normally in the form of yarn bundles, to forward the yarn, to entangle or interlace filaments of the bundle for a particular appearance or physical characteristic, or to texturize or bulk the filaments.
In similar fashion, fluid jet structures have heretofore been utilized to both forward and attenuate thermoplastic filaments of a yarn bundle, preparatory to deposition of the yarn bundle onto a moving substrate, for formation of a nonwoven web. The web is then calendered or otherwise treated to unify same into a coherent structure. One particular type of process for so forming a nonwoven web is referred to as a "spunbond" process which involves deposition of filamentary materials onto a support surface without intermediate collection of the materials, and it is this particular type of process for which the improved yarn forwarding and drawing apparatus of the present invention is particularly suited. Fluid jet structures that have been utilized for the drawing and forwarding of thermoplastic filamentary materials in a spunbond type process are exemplified by U.S. Pat. Nos. 3,655,862 to Dorschener et al; 3,576,284 to Fellous et al; 3,754,694 to Reba; and 3,736,211 to Lipscomb et al.
A number of fluid devices are normally employed at adjacent spinnerettes along a melt spinning apparatus, with the combined filamentary output through the adjacent devices spanning the width of the web to be formed. Overall uniformity of physical characteristics of the filaments being deposited is important to production of a uniform web. Heretofore, fluid drawing and forwarding devices have, of necessity, been manufactured within very close tolerances, attempting to produce precision devices through which filaments of uniform physical properties are processed. Trial and error and/or selection techniques have generally been necessary, however, attempting to match such precision devices, without totally satisfactory results. Oftentimes, for example, particular units have been discarded due to inability to process filaments that exhibit physical properties within the specification ranges for same.
Prior art fluid operated devices for forwarding and/or other processing of filamentary yarns have employed a venturi of Laval type nozzle structure. Yarn is presented in a yarn passageway of a guide tube that is centrally located with respect to the nozzle structure with the tip of the yarn tube residing in and cooperating with the structure to provide an aspirating nozzle. Primary pressurized fluid passing through the nozzle structure aspirates atmospheric air through the guide tube to entrain and forward the yarn, while the primary fluid acts on the yarn in its intended manner, to interlace, bulk, texturize, attenuate or otherwise affect the filaments. Primary fluid flow has been generally turbulent or nonturbulent, depending upon whether the filaments are to be tangled or parallel. In general, however, such devices are deficient or inefficient in some respect, such as noise level during operation, requirements for high fluid pressures, high fluid consumption, inability to process yarns traveling at high linear velocities, unreasonable manufacturing tolerances, lack of uniformity of filaments processed through adjacent devices, and the like.
Fluid operated devices for both forwarding and drawing organic filamentary yarns according to the present invention, achieve the intended results without experiencing the deficiencies or inefficiencies noted above. Numerous significant parameters have been considered and are achievable by the device and process of the present invention. Filaments up to 15 denier and filament bundles up to 1500 total denier may be satisfactorily forwarded and drawn at linear velocities through the device up to about 7500 meters per minute. At operating speeds of the magnitude mentioned above, the bundle is forwarded and drawn without entanglement or interlacing of the filaments. The yarn bundle does not make any significant contact with the side walls of the friction tube. The devices are capable of accurate adjustment during operation which permits matching of devices located at a plurality of adjacent extrusion positions which supply filaments for the width of a web to be formed. The apparatus operates satisfactorily at low air pressures, low air consumption, and at low noise levels. Good aspiration of secondary air and attainment of adequate tensioning on the filaments for drawing are simultaneously achieved. Components of the devices are interchangeable.
The device and method according to teachings of the present invention accomplish the aforestated results and operational characteristics. Clearly such represents significant technological improvement over prior devices and techniques. The known prior art neither teaches nor suggests the novel structure or process according to the present invention.